The present invention relates generally to network interfacing and, more particularly, to an apparatus and method for connecting multiple networks, each of which is implemented on unique telephone line, to form a common network.
Networking plays a critical role in the sharing of information from between two remotely located computing devices. Government bodies and business entities heavily utilize local and wide area networks to communicate and share information. A typical government or commercial facility includes an Ethernet network with a physical topology utilizing Category V cabling. Category V cabling is a shielded cabling specifically designed to reduce distortion of high frequency data signals. Further, a typical government or commercial facility includes a separate and distinct PBX network for telephone calls. For many reasons, the Ethernet data network and the PBX network are separate networks. These reasons include network physical topology, conflicts between Ethernet and PBX environments, and other fundamental incompatibilities between Ethernet protocols and PBX protocols. Until the recent development of Voice over IP standards which enable packet voice communications over a data network, little thought was given to combining such systems into a single network.
In a home environment, a PBX system is not normally used and a plain old telephone service (POTS) network of twisted pair wires typically connects a plurality of RJ-11 jacks throughout the home to a POTS line coupled to a local telephone switch. The POTS line can support a single connection (e.g. telephone conversation or modem dial-up connection) at any one time. Therefore, while the POTS network in the home may be a single-bus-multiple-drop physical topology with a plurality of device connected thereto, only one connection at time may be made through the local telephone switch.
Recently, there has been an increased demand for networking of multiple computing devices within a home environment. Many households have multiple PC computers, printers, and other shared peripherals. Further, there is a growing demand for other home electronics and appliances to have networking capabilities such that they can be monitored and controlled from remote locations. An obvious desire is to utilize the POTS network within the home for data networking. Homes already have an infrastructure of telephone wires built into their walls; there is no need to re-wire homes with more expensive conventional networking wiring. Further, the high speed data capabilities of conventional data networks typically are not needed because the sharing of data between home PC""s and other home electronics such as smoke detectors, burglar alarms, ovens, light fixtures, sprinkler systems, and the like does not require fast data rates or high data volumes. The less expensive, and existing, twisted pair telephone lines will suffice as a medium to transmit data between these types of network devices.
The Home Phone Line Networking Association (HPNA) is a consortium of companies, including Advanced Micro Devices of Sunnyvale Calif., which has developed communications protocols and networking standards for transmitting data between two devices across the POTS system of a home. The HPNA system enables multiple devices, each connected to the telephone line in a multi-drop architecture, to communicate with each other. In the HPNA 1.0 environment a pulse position modulation (PPM) system is utilized and in the HPNA 2.0 environment, a 7 MHz quadrature amplitude modulated (QAM) modulated carrier is utilized as well as the PPM system. Further, a telephone can communicate with a local telephone switch utilizing POTS 0.3-3.4 KHz signals at the same time various computing devices are communicating with each other utilizing the HPNA 1.0 or 2.0 schemes. The HPNA 1.0 and 2.0 systems enable many devices to communicate frames of data with each other using a carrier sense multiple access (CSMA) protocol.
The problem with implementing an HPNA data network environment in a home environment is that many homes are wired with two or more separate phone lines, each with its own distinct POTS network throughout the home. Each POTS network is independent and separate of other networks to enable each to have a distinct telephone number and telephone service independent of the other lines. As such, HPNA data can not cross from one POTS network to another. If the POTS networks were coupled together, the voice signal of one telephone line would cross over and interfere with the voice signal of another telephone line.
Therefore, based on recognized industry goals for efficient and effective networking in a multiple POTS environment, a device and a method is needed to couple multiple POTS networks to form a common data network to transmit and receive data among network devices while preventing interference between telephone signals unique to each POTS line.
A first object of the present invention is to provide a local area network comprising at least two separate and unique telephone lines and a coupling device for connecting multiple separate and unique telephone lines. The local area network may comprise a network medium of twisted pair telephone wires, which is used to connect a plurality of network devices via RJ-11 jacks. The network devices may include computers, smoke detectors, burglar alarms, ovens, light fixtures, sprinkler systems, and the like.
The local area network may further include a telephone for making telephone calls independent of transmissions and receptions among the network devices. A telephone and a number of network devices connected to the network medium of twisted pair telephone wires form one separate and unique xe2x80x9cline onexe2x80x9d. Another telephone and another number of network devices connected to the network medium of twisted pair telephone wires form a second separate and unique xe2x80x9cline twoxe2x80x9d. The telephone calls operate utilizing plain old telephone service signals in a frequency range of 0.3-3.4 KHz. The network devices transmit and receive data signals which include frames of data modulated onto an analog carrier. The modulation technique may include quadrature amplitude modulation and pulse position modulation.
The coupling device may comprise a first transformer coupled to a first of the telephone lines and second transformer coupled to a second of the telephone lines and a high pass or a band pass filter coupled between the first and second transformer.
A second object of the present invention is to provide a method of coupling data between two telephone networks. The method comprises the steps of: a) generating telephone signals on a first telephone network; b) generating data signals on at least one of the first and a second telephone network; c) passing data signals between the first telephone network and the second telephone network; and d) isolating telephone signals on the first telephone network from the second telephone network.
The step of generating telephone signals may include generating plain old telephone service signals in a frequency range of 0.3-3.4 KHz and the step of generating data signals may include generating frames of data modulated onto an analog carrier. The modulation technique may include quadrature amplitude modulation and pulse position modulation.
The step of passing data signals may include utilizing a first transformer coupled to the first telephone network and second transformer coupled to the second telephone network and a high pass filter or a band pass filter coupled between the first and second transformer.
A third object of the present invention is to provide a coupling device for providing selective coupling between at least two individual telephone networks. The coupling device comprises: a) a first set of terminals for connecting the coupling device to a first one of the at least two individual telephone networks; b) a second set of terminals for connecting the coupling device to a second one of the at least two individual telephone networks; and c) a filter operatively coupled to the first and second set of terminals and tuned to pass there between a predefined band of signal frequencies associated with network data communications and to block there between a predefined band of signal frequencies associated with audio communications.
The signal frequencies associated with audio communications may include plain old telephone service signals in a frequency range of 0.3-3.4 KHz and the signal frequencies associated with network data communications may include modulated carrier signals with a carrier frequency greater than 1 MHz.
The filter may include a first transformer coupled to the first set of terminals and a second transformer coupled to a second of terminals and a high pass filter or a band pass filter coupled between the first and second transformer.